David Cameron has appointed his senior security adviser to lead a new drive for compensation for British victims of IRA terrorism.

The Prime Minister has asked Sir Kim Darroch to negotiate with Libya in an effort to secure money for the families of those who died or were maimed in republican attacks that used plastic explosive supplied by Colonel Muammar Gaddafi’s regime.

It follows a Telegraph investigation which showed how an intervention by Tony Blair led to a deal in which US victims of IRA bomb attacks received millions of pounds in compensation from Libya, while British victims received nothing.

Pressure is growing on Downing Street to secure greater help for British families affected by Irish republican terrorism. On Saturday, a series of senior politicians, including Lord Tebbit, Lord Mandelson and Boris Johnson, lent their support to a concerted new campaign to end what has been described as a “disgraceful” injustice.

The devastation wreaked by the IRA in Northern Ireland on the mainland came to prominence again last week with the arrest of Gerry Adams, the president of Sinn Féin, over the murder of a mother of 10 children in Belfast in 1972.

On Saturday Mr Adams continued to be interviewed by police for a third day.

Last week, Mr Cameron met informally senior Unionist politicians, including Peter Robinson, the First Minister, over the issue of compensation. According to one MP present, Mr Cameron promised “to lead a reinvigorated effort” in the case.

Nigel Dodds, the deputy leader of the Democratic Unionist Party, said after the meeting: “This provides us with an opportunity to breathe fresh momentum into the Libyan compensation case.”

Mr Cameron told the Unionists he would meet victims’ representatives and was appointing Sir Kim, his National Security Adviser, “to make progress on the issue”.

Mr Dodds added: “I have pressed David Cameron for a further meeting with victims. It is important he hears directly from the victims themselves.”

As disclosed by the Telegraph earlier this year, political interference led to the collapse in 2008 of a class action claim being brought against Libya by 150 victims of the IRA in the US courts.

As a result of a deal, in which Mr Blair intervened on Gaddafi’s behalf, US victims of Libyan terrorism — including victims of IRA bombings — received a share of £1 billion paid out by Libya. However, British victims were excluded and have received nothing.

Victims’ anger has been compounded by the disclosure that IRA suspects on the run had received letters effectively granting them immunity in a move authorised by Mr Blair to keep the Good Friday peace deal on track.

Victims are now demanding a full investigation into the deals done by the previous government, which they say have deprived them of justice and recompense for injuries and deaths.

On Saturday, Mr Johnson, the London Mayor, said: “This is a totally disgraceful set of circumstances. The previous government buttered up to Gaddafi’s regime in Libya instead of going after terrorists. It is nauseating.

“It is certainly not right that there should be one regime of compensation applying to citizens of the US and another for British victims.”

Lord Tebbit, whose wife was left wheelchair-bound when the IRA bombed the Grand Hotel in Brighton during the Conservative Party conference in 1984, said: “This is a sordid affair which has had a terrible detrimental effect on the victims. There should have been compensation for victims and there would have been had it not been for Blair and the Labour government making bargains with Gaddafi.”

Lord Tebbit said he backed any campaign that called for greater transparency over the issue.

Lord Mandelson, who was the most senior minister in Gordon Brown’s Cabinet and a former Northern Ireland secretary under Mr Blair, also backed the victims’ campaign. He said he had held talks with Libya on compensation for victims of IRA terrorism while he was a minister and urged Mr Cameron to renew efforts to reach a settlement.

Securing compensation from the Libyan government would “be a strong gesture of goodwill and recompense and would mean a lot”, he added.

It is understood that the Prime Minister is receptive to compensation being paid by the Libyan government in recognition of Gaddafi’s role in sponsoring IRA terrorism.

Options include a one-off payment, although there is a recognition that stability needs to return to Libya before any deal could be reached. After Gaddafi’s fall in 2011, an interim government committed Libya to paying damages to IRA victims, but since then the country has fallen into chaos.

A spokesman for Downing Street said the Prime Minister had praised the efforts of Mr Robinson, Mr Dodds and Jeffrey Donaldson MP to ensure that victims and their families were not forgotten and acknowledged “the deep wounds that people affected still feel”.

“The UK Government continues to urge the Libyan authorities to engage with UK citizens affected by Gaddafi-sponsored terrorism,” the spokesman added.

“The Libyan authorities are in no doubt of the importance the UK attaches to resolving this and other outstanding legacy issues arising from the actions of the Gaddafi regime.

“The Prime Minister confirmed he was committed to achieving the objective of broad and lasting reconciliation between Libya and UK communities affected by Gaddafi’s sponsorship of IRA terrorism and that he would ensure that this issue is given the attention its deserves across government.” The role of the former government and the involvement of Mr Blair, when out of office, were disclosed in an email obtained by the Telegraph.

The email sent by Sir Vincent Fean, the then British ambassador to Libya, to Mr Blair’s private office in June 2008 showed how Mr Blair, a frequent visitor to Libya, had been enlisted by Gaddafi to help him in negotiations with President George W Bush.

The consequence of that deal, signed two months later, was to leave UK citizens out of the compensation agreement.

Sir Vincent added in his email: “HMG is not involved in the talks, although some British citizens might be affected by them (... some UK Northern Irish litigants going to US courts seeking compensation from Libya for IRA terrorist acts funded/fuelled by Libya).”

Colin Parry, whose son Tim, 12, died when a bomb using Libyan-supplied plastic explosive detonated in Warrington town centre, has described the deal which deprived him and other families of compensation as “grubby”.

On Saturday, Matthew Jury, a managing partner at McCue and Partners, who represented families in the class action lodged in the US, said: “We welcome the news that, after a long campaign, the Prime Minister has now agreed to meet with UK victims of Libyan IRA terrorism who, for so long, have been denied justice and compensation.

“The Prime Minister’s assurance that officials are working to progress this is encouraging.”

Mr Blair has categorically denied interfering in the legal cases that were being brought in the US against Gaddafi’s regime.

A spokesman for Mr Blair said: “The email you refer to does not say what you allege. It merely refers to the fact that once the issue was resolved between the US government and the Libyan government — not an issue for Tony Blair or the UK but for those two Governments — it was important to move on to areas of cooperation so that Libya could be part of the international community not hostile to it.

“The idea that Tony Blair as UK Prime Minister would argue to remove UK victims from the terms of compensation is absurd.”